Family-friendly Yahoo is finally cracking down on all that Tumblr porn. The company this week made adult Tumblr blogs entirely unsearchable, both internally and on the Web—effectively blacking out those blogs forever.

Before the $1.1 billion Yahoo acquisition, Tumblr was home to a lot of porn. In May, analysts at SimilarGroup estimated that 11.4 percent of Tumblr’s top 200,000 blogs contained adult content.

CEO Marissa Mayer tap-danced around the porn question in the days following the acquisition, telling analysts at one point, “The richness and breadth of the content… is what makes it more exciting. In terms of addressing concerns around brand safety we need to have good tools for [ad] retargeting.”

With this week’s decision, Yahoo instead decided to uncouple those blogs from the Internet.

Existing porn blogs on Tumblr are no longer searchable. New users searching Tumblr for adult keywords won’t see any results, either on the Tumblr site or through search engines.

New porn bloggers on Tumblr will find it difficult to build an organic audience, and will likely move on to a different, more porn-friendly blogging platform.

Earlier this month, Mayer posted on her own Tumblr blog that the site was experiencing incredible growth since Yahoo’s acquisition, averaging 80 million new posts each day. The hope, perhaps, is that by cracking down on porn, Yahoo will turn Tumblr into a more mainstream blogging platform.

They do so at the risk of alienating Tumblr’s core audience, who built the site (at least partly) on porn.